Method of Modifying the Region Displayed Within a Digital Image, Method of Displaying an Image at Plural Resolutions, and Associated Device

1. A method of modifying a region displayed in a window of predetermined size within a digital image represented by several resolution levels, from a first region of the digital image displayed at a first resolution to a second region of the digital image including the first region and different from the first region, comprising the steps of: selecting, from stored image parts each including the first region, a stored image part with a second resolution that is the maximum among the resolutions of said stored image parts, and that is less than the first resolution; obtaining from the selected image part at least one region included in the second region and including the first region; and displaying the obtained region in said window.

2. A method according to claim 1 , further comprising a step of determining the second region on the basis of the selected image part.

3. A method according to claim 2 , wherein the determining step comprises a step of defining the selected image part as the second region.

4. A method according to claim 3 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the defining step is implemented when said maximum resolution is equal to the resolution of the second region.

5. A method according to claim 2 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the determining step comprises a step of defining a region centered on the first region as the second region when said maximum resolution is strictly less than the resolution of the second region.

6. A method according to claim 2 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the determining step comprises a step of defining a region centered on a point of the first region indicated by the user as the second region when said maximum resolution is strictly less than the resolution of the second region.

7. A method according to claim 1 , wherein the obtaining step comprises the obtainment of a plurality of regions included in the second region and including the first region, and wherein the obtaining step comprises a successive display of the plurality of obtained regions.

8. A method according to claim 1 , wherein the obtaining step comprises a step of over-sampling by a specific factor.

9. A method according to claim 1 , wherein the digital image is represented at each resolution level in an encoded format.

10. A method according to claim 9 , wherein said stored parts of the image result from a prior step of decoding in accordance with said format.

11. A method according to claim 1 , further comprising the steps of: decoding data relative to the second region; and on the basis of the decoded data, displaying the second region after the display of the obtained region.

12. A method according to claim 1 , wherein the image parts are stored in the form of bitmaps.

13. A method according to claim 1 , wherein the stored image parts are stored locally.

14. A method of displaying an image at plural resolutions based on hierarchical encoded data representing said image, comprising: a first displaying step for displaying at least a part of the image at a first resolution, image data used for displaying said part at the first resolution being stored; a second displaying step for displaying at least a part of the image, at a second resolution higher than the first resolution, after the first displaying step; and a third displaying step for displaying at least a part of the image, at a third resolution lower than the second resolution, after the second displaying step, the part displayed in the third displaying step including the part displayed in the second displaying step, wherein a position of the part displayed in the third displaying step is determined, irrespective of the position of the part displayed in the second displaying step within the part displayed in the third displaying step, so that the part is displayed in the third displaying step by using the stored image data.

15. A device constructed to modify a region displayed in a window of predetermined size within a digital image represented by several resolution levels, from a first region of the digital image displayed at a first resolution to a second region of the digital image including the first region and different from the first region, comprising: means for selecting, from stored image parts each including the first region, a stored image part with a second resolution that is the maximum among the resolutions of said stored image parts, and that is less than the first resolution; means for obtaining from the selected image part at least one region included in the second region and including the first region; and means for displaying the obtained region in said window.

16. A device according to claim 15 , further comprising means for determining the second region on the basis of the selected image part.

17. A device according to claim 16 , wherein the determining means comprise means for defining the selected image part as the second region.

18. A device according to claim 17 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the means for defining the selected image part as the second region operate when said maximum resolution is equal to the resolution of the second region.

19. A device according to claim 16 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the determining means comprise means for defining a region centered on the first region as the second region when said maximum resolution is strictly less than the resolution of the second region.

20. A device according to claim 16 , wherein the resolution of the second region is determined on the basis of the resolution of the first region, and wherein the determining means comprise means for defining a region centered on a point of the first region indicated by the user as the second region when said maximum resolution is strictly less than the resolution of the second region.

21. A device according to claim 15 , further comprising: means for decoding data relative to the second region; and means for displaying, on the basis of the decoded data, the second region after the display of the obtained region.

22. A device according to claim 15 , wherein the stored image parts are bitmaps.

23. A device according to claim 15 , further comprising means for local storage of the stored image parts.

24. A device for displaying an image at plural resolutions based on hierarchical encoded data representing said image, comprising: first displaying means for controlling display of at least a part of the image at a first resolution, including storing means for storing image data used for displaying said part at the first resolution; second displaying means for controlling subsequent display of at least a part of the image, at a second resolution higher than the first resolution, and third displaying means for controlling subsequent display of at least a part of the image, at a third resolution lower than the second resolution, the part displayed by the third displaying means including the part displayed by the second displaying means, including means for determining a position of the part displayed by the third displaying means, irrespective of the position of the part displayed by the second displaying means within the part displayed by the third displaying means, so that the part is displayed by the third displaying means by using data from the storing means.

25. A non-transitory data storage means storing computer program code instructions for executing the steps of a method according to claim 1 .

26. A computer program stored on a non-transitory computer-readable medium, containing instructions such that, when said program controls a programmable data processing device, said instructions cause said data processing device to implement a method according to claim 1 .